Contemporaries called him "Satan incarnate" and "the most impious atheist who ever lived upon face of the earth." But he is now revered as arguably the greatest philosopher since Plato, as the political theorist who first enunciated the general principles for a secular democratic society, and in many ways a modern saint. Baruch, later Benedict, de Spinoza (1632-77) devoted his adult life to thinking about the biggest questions of all: the nature of God and the universe, the function of religion, man's elusive quest for happiness, the ideals of government, how we should conduct our lives. His own was one of absolute simplicity -- a rented room, a little gruel for supper, an occasional pipe of tobacco, most of it paid for by his small earnings as a lens-maker. But, as the poet Heinrich Heine said, "All our modern philosophers . . . see through the glasses which Baruch Spinoza ground."

"Expelled from the Jewish community of his day, Spinoza went on to construct a lasting philosophy."

As with Shakespeare, we know very little about his early life and nowhere near enough about his maturity. So his biographers have closely examined the world he grew up in, that of Jews who had fled the Inquisition in Spain for the relative tolerance of the 17th-century Netherlands. As a youth, Spinoza was trained in the traditions of Talmudic scholarship but also introduced to the seductive mysticism of the Kabbalah. His teachers obviously expected great things from him. Nonetheless, by his early twenties Spinoza began to voice opinions judged heretical. He refused to keep quiet and was finally, dramatically excommunicated from the Jewish community with the rite of cherem, cutting him off from his friends, family and community. For the rest of his 44 years, Spinoza lived as a Dutch citizen and a philosopher.

In Betraying Spinoza , the novelist and professor of philosophy Rebecca Goldstein aims to show how much his heritage nonetheless pervades his later thought. To do this, she offers both a precis of Spinoza's life and work and a history of her fascination with both. In fact, Goldstein opens her book by recreating one of her childhood religion classes, when she first heard about this terrible "renegade Jew" from a Mrs. Schoenfeld. "Spinoza had the arrogant love of his own mind, Mrs. Schoenfeld continued. . . . Atheism always comes down to arrogance. Remember that, girls." To my mind, Goldstein errs in adopting this over-personal approach, but she is obviously working hard to make a difficult thinker appealing to common readers.

Perhaps the closest we come to understanding the young Spinoza's intellectual restlessness lies in the practically confessional opening to one of his early treatises, On the Improvement of the Understanding . "After experience had taught me that all the usual surroundings of social life are vain and futile; seeing that none of the objects of my fears contained in themselves anything either good or bad, except in so far as the mind is affected by them, I finally resolved to inquire . . . whether, in fact, there might be anything of which the discovery and attainment would enable me to enjoy continuous, supreme, and unending happiness." What a dreamer! Who expects "continuous, supreme and unending happiness" in life? But in his Ethics, Spinoza ends with just such a vision of earthly serenity.

Many people have been put off the Ethics because it is organized like Euclid's Elements (and originally written in Latin). The thought progresses through axioms, propositions, definitions, proofs. While studying such pages, one frequently longs for the engaging style of Descartes or the baroque grandeur of Hobbes (two near contemporaries from whom Spinoza learned). Persevere. The appendices to each of the five sections of the Ethics and the periodic mini-essays called scholia provide short, even lively summaries of the arguments. Spinoza recognizes that he needs what he himself calls his "cumbersome, geometric order." People, he shows, are constantly being led astray by the randomness of their sensual experience, by their imaginations and passions. Only mathematics provides a model for conclusions that cannot be refuted, that are either right or wrong: "I will write about human beings as though I were concerned with lines and planes and solids."

Surprisingly, the Ethics opens by establishing basic truths about God and nature. Everything that exists is part of the single substance of the deity, who, in fact, is identical with Nature, or as Spinoza invariably writes "God, or Nature." Because everything is inherent in God eternally, there are no goals or ends for man or the universe. As Matthew Stewart says in The Courtier and the Heretic (Norton), a highly recommended new biographical study of Spinoza and Leibniz, "To the fundamental question -- what makes us special? -- Spinoza offers a clear and devastating answer: nothing."

From this rather bleak beginning, the philosopher nonetheless goes on to lay out his Ethics proper. Human psychology, he determines, is based entirely on self-interest and self-preservation, while being largely subject to ever-changing combinations of desire, pleasure and pain. Such domination by the changeable senses and the outside world inevitably results in emotional turmoil: "Like waves on the sea, driven by contrary winds, we toss about, not knowing our outcome and our fate." To overcome this "human bondage" to ephemeral passions, we should learn to moderate our desires, live according to reason and ultimately aspire to a kind of intellectual love of God. This acceptance of the universe as it is will create an inner peace of mind, or "blessedness," during life and permit a kind of impersonal immortality after death.

Part of Spinoza's prescription for true happiness may sound familiar. The ancient Greeks advocated a stoic indifference to the world's ills; St. Augustine confessed that our hearts are restless until they rest in God; Buddhists believe that we must free ourselves from the wheel of desire to find spiritual beatitude. Unlike these austere systems, however, Spinoza's doesn't reject the body or the delights of the world: "It is the part of a wise man, I say, to refresh and restore himself in moderation with pleasant food and drink, with scents, with the beauty of green plants, with decoration, music, sports, the theater, and other things of this kind, which anyone can use without injury to another. For the human body is composed of a great many parts of different natures, which constantly require new and varied nourishment." And we should strive to be cheerful too: "Why is it more proper to relieve our hunger and thirst than to rid ourselves of melancholy?"

It is just this combination of rigorous thinking and deep, kindly humanity that makes Spinoza such an appealing figure. Indeed, Goldstein tells us she was initially drawn to Spinoza because of an act of shalom bayit , which means peace within the household: The youthful firebrand waited until his father was dead before he began to break with the Jewish community. "He had not wanted to hurt his family by speaking his doubts aloud," she writes. "Though he was a man who had given himself over entirely to the search after truth -- I knew this instinctively -- still he would not speak the truth so long as his doing so might hurt those whom he loved."

Long ago, Will Durant wrote of the Ethics in his Story of Philosophy , "When you have finished it a second time you will remain forever a lover of philosophy." Yet during the first 100 years after Spinoza's death, he was best known for his other major work, the Theological-Political Treatise . This is an impassioned attack on superstition and a defense of tolerance and democratic principles. All too often, Spinoza points out, people "pay homage to the Books of the Bible, rather than to the Word of God." In fact, the only real message of any true scripture is simply to know and love God and to love one's neighbor as oneself. As a result, "in judging whether or not a person's faith is pious, we must look only to his works. If they are good, his faith is as it should be." As Stewart points out in The Courtier and the Heretic , Spinoza "argues that men who live under the guidance of reason invariably treat others with respect, they repay hate with love, and in general behave like model citizens and 'good Christians.' "

Unfortunately, so long as most men are swayed by passions, we require the state to ensure our security. To Spinoza, a democratic republic will best maintain the rights of all its citizens, and his ideas slowly percolated down to political philosophers such as John Locke and the revolutionaries who dreamt up the United States. In particular, he argues for free speech and utter openness in government: "Better that right counsels be known to enemies than that the evil secrets of tyrants should be concealed from the citizens. They who can treat secretly of the affairs of a nation have it absolutely under their authority; and as they plot against the enemy in time of war, so do they against the citizens in time of peace."

There's much more beauty and truth to Spinoza than I have clumsily summarized here. Goldstein's Betraying Spinoza offers a convenient way to start exploring his thought more fully, though I would also urge ambitious readers to pick up Steven M. Nadler's magisterial biography, Spinoza: A Life (Cambridge, 1999), and then plunge into the works themselves. Spinoza is worth the effort: "He who rightly knows that all things follow from the necessity of the divine nature, and happen according to the eternal laws and rules of Nature, will surely find nothing worthy of hate, mockery, or disdain. . . . Instead he will strive, as far as human virtue allows, to act well, as they say, and rejoice." ·

Michael Dirda's "Book by Book: Notes on Reading and Life" has just been published. His email address is mdirda@gmail.com.

Een vijfdelige radioshow van Radio Wisconsin gaat in op Wetenschap & Religie. In de show wordt ook Goldstein geïnterviewd. De show is als podcast te downloaden vanaf de site van Wisconsin Public Radio.